Valve membrane



FIG. 1 is a front top perspective view of a valve membrane according to our design;

FIG. 2 is a front bottom perspective view thereof;

FIG. 3 is a front elevational view thereof, the rear elevational view being a mirror image thereof;

FIG. 4 is a right side elevational view thereof, the left side elevational view being a mirror image thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof. 

CLAIM The ornamental design for a valve membrane, as shown and described. 